Semiconductor packages are commonly used to house and protect integrated circuits, such as amplifiers, controllers, ASIC devices, sensors, etc. In a semiconductor package, an integrated circuit (or circuits) is mounted to a substrate. The semiconductor package typically includes an electrically insulating encapsulant material, such as plastic or ceramic, that seals and protects the integrated circuits from moisture and dust particles. Electrically conductive leads that are connected to the various terminals of integrated circuits are accessible outside the semiconductor package.
In some package designs, the package substrate is configured as a so-called “heat slug” or “heat sink.” A package level heat slug is designed to pull heat away from the integrated circuit. Typically, the heat slug is formed from a thermally conductive material (e.g., metal). In some package configurations, the heat slug also serves as an electrical terminal that provides a reference potential (e.g., ground) to the dies that are mounted thereon.
Designers are continuously seeking to improve packaging designs. One notable design consideration that is gaining considerable attention is the total footprint of the package. As technology progresses, there is a strong demand to reduce the size and/or cost of most electronic components. Another notable design consideration is heat dissipation. Heat consumption per area of modern integrated circuit devices continues to increase as devices become faster and more powerful while simultaneously becoming smaller. As a result, there is much greater emphasis on cooling solutions to prevent modern integrated circuits from failure or decreased performance due to overheating. The desire to reduce the total footprint of the package often conflicts with the desire to optimize the heat dissipation of semiconductor packages, as larger heat sinks are typically used to provide more cooling.
RF Applications present unique challenges with respect to package design. Many packaged RF devices include two or more integrated circuits and corresponding bond wires that connect the integrated circuits to the package leads. As these integrated circuits typically operate at high frequency, there is a substantial likelihood of inductive coupling between the bond wires. This inductive coupling can cause interference that can degrades signal integrity, and can even cause complete failure. As package sizes continue to decrease, this issue presents a greater challenge as electrical isolation between the different integrated circuits becomes harder to achieve. Current isolation techniques include providing shield structures between the various integrated circuits of the package. However, these shield structures utilize value package space.